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terry

wrote:
Can anyone tell me why I would get a 27 volt reading on a 120v circuit.
I have a old home but some of the home has been re-wired. I am
remodeling my bath room and removed old florescent lights. I tested
the power at the connections and got a reading of 27v. I climbed in
the attic and it looks like the wire is coming from a junction box with
several other wires. It looks like the work was done by a pro. The
upstairs has 2-20amp (connected together) circuits.
..
Some replies are making this too complicated. Forget the volts and amps
and impedance stuff.

Your question has been asked frequently here; it's sensible one but
usually asked by someone without much electrical experience and
training and almost always involves voltage read with one of those
digital display meters.

Non technical reply:

Digital meters are so sensitive (even the cheapest ones) that they can
pick up voltages induced into even dead/disconnected wires from
adjacent working/activated wires.

In some circumstances they can pick up the faint voltages of the
multitude of radio and wireless-device waves that surround us these
days! Even if a wire is grounded at the far end it can still act as an
antenna at many frequencies and thus pick up enough electrical energy
to read 'something' on a meter. Depends on the location, radio field
strengths the meter etc.

Heck; I have one meter sensitive enough that, if I touch the leads with
my fingers it will pick up enough energy for a reading even if I'm
standing in my basement. Hook it up to a spare coil of wire hung up and
not connected to anything and one gets a higher reading again.

For house AC work a spare bulb screwed in a lamp socket with a couple
of leads is often the best way to test whether a wire is permanently
'live' from the AC breaker/fuse panel, is (switch on/off) switched
live, a neutral or a ground.

The mention of two 20 amp circuits 'connected together' is confusing.
It also might be confusing/unsafe for anyone working on that/those
circuits; my understanding is that once the breaker/fuse for a circuit
is off/removed there should be no other power (from another connection
circuit etc.) to anything on that circuit or in the same AC boxes.
That's a little worrying and possibly not up to code? Possibly an
insurance concern?

Maybe you mean two 'separate' 20 amp circuits; or is the breaker a
'double 20 amp' with the handles connected together so that both
breakers will trip at same time?????????